The objective is to study a new animal model of diabetes which appears spontaneously in a particular colony of rats ("BB"). The diabetes is characterized by insulin dependence and ketosis and is thus similar to human juvenile diabetes, unlike all other rodent diabetes models except the Chinese hamster. Pathogenesis of the disease will be studied with special emphasis on genetic background, and possible viral and/or autoimmune etiology. Treatment of the diabetes and its possible complications will be attempted by islet and pancreas transplantation. These techniques will also be used to define the roles of specific islet failure vs. a generalized disease process as possible explanations of the syndrome.